<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script language="javascript">
        //手工输入一年份，判断是否是闰年
        var year = prompt('请输入年份',''); 
        if(year%100 ==0){
           if(year%400 ==0){
             document.parseInt(year+"年是闰年");	 
           } 
        }else if(year%4 ==0){
             document.write(year+"年是闰年"); 
          }else{
           document.write(year+"年不是闰年");	 	
        }
         </script>
</body>
</html>